Method and an apparatus for compacting a loosely packed layer of earth

ABSTRACT

A method of compacting a loosely packed layer of earth. According to this method a tube is vibrated into the earth, which tube accommodates a closing member at a distance from the underside of the tube which substantially corresponds to the distance from the ground level to the upper side of the layer of earth to be compacted. Earth is received in the tube while this tube is being vibrated into the earth, until this earth within the tube strikes the closing member at the time that the underside of the tube has reached approximately the upper side of the layer of earth to be compacted. Hereupon, in the further course of the tube being vibrated downwardly to the required depth, earth is displaced in the layer of earth to be compacted, whereafter the tube is vibratingly lifted and the earth which has been received in the tube leaves the tube and is left in the ground. An apparatus for carrying out this method consists of a tube within which a closing member is accommodated at the appropriate distance from the underside of the tube. This closing member is pervious to air.

van Weele Jan. 23, 1973 METHOD AND AN APPARATUS FOR COMPACTI NG ALOOSELY PACKED LAYER OF EARTH 75] 'i'iweHiB'n 11am i iiiiebisvanWeele,Wad-

[73] Assignee: N. V. tot Aanneming van Werken voorheen H. J. Nederhorst,Gouda, the Netherlands 221 Filed: Jan. 13,1971

21 App1.No.: 106,090

[30] Foreign Application Priority Data Jan. 14, 1970 Netherlands..7000539 [52] US. Cl. ..61/36 R [51 Int. Cl. ..E02d 3/06 [58] Field ofSearch ..6l/35, 36, 11,63, 53.64; l75/19,55,56

[56] References Cited UNITED STATES PATENTS 3,498,066 3/1970 Nishimuraet al. ..6l/35 X 2,719,029 9/1955 Steuerman ...61/36 R X 2,576,50711/1951 Gerwick,Jr. ..6l/63 3,352,160 11/1967 Mount ..l75/56 X 3,540,22511/1970 Muller 6l/53.64 X

3,608,317 9/1971 Landau ..6l/35 X dinxveen. Netherlands PrimaryExaminer-David J. Williamowsky Assistant Examiner-Philip C. KannanAttorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT A method ofcompacting a loosely packed layer of earth. According to this method atube is vibrated into 'the earth, which tube accommodates a closingmember at a distance from the underside of the tube which substantiallycorresponds to the distance from the ground level to the upper side ofthe layer of earth to be compacted. Earth is received in the tube whilethis tube is being vibrated into the earth, until this earth within thetube strikes the closing member at the time that the underside of thetube has reached approximately the upper side of the layer of earth tobe compacted. Hereupon, in the further course of the tube being vibrateddownwardly to the required depth, earth is displaced in the layer ofearth to be compacted, whereafter the tube is vibratingly lifted and theearth which has been received in the tube leaves the tube and is left inthe ground.

11 Claims, 3 Drawing Figures Displacement compacted Probing rlsistanEPATENIED JAN 23 1975 SHEET 1 BF 2 ststance Displacement compactedProbing re mS E 5 53a V PATENTEDJAH 23 I975 SHEET 2 OF 2 METHOD AND ANAPPARATUS FOR COMPACTING A LOOSELY PACKED LAYER OF EARTH BACKGROUND OFTHE INVENTION The invention relates to a method of compacting a looselypacked layer of earth as well as to an apparatus for carrying out thismethod.

According to a known method of compacting loosely packed, non-cohesivelayers of earth at a great depth, a vibrator is-introduced into theearth, which vibrator consists of a steel cylinder closed at its lowerend with a conical point and attached at its upper end to extensionelements via an elastic coupling. The vibrator contains an electricmotor which, in operation, drives eccentric impact weights, causing avibrating motion to be imparted to the vibrator. The vibrator is loweredby supplying water at the point, causing it to descend by its ownweight. As soon as the required depth has been reached, the supply ofwater near the point is shut off, whereupon the water is discharged atthe neck of the vibrator. Hereafter, the process of compaction beginsand in order to prevent undue subsequent sagging of the ground surface,additional sand is continuously dumped from above. When adequatecompaction has been achieved at the required depth, the vibrator and theextension elements are drawn upward by a few decimeters, whereupon theaforementioned operation is repeated. A zone of compacted earth, inparticular sand is thus built up.

However, in particular when layers of high density are present abovesaid layers of earth to be compacted,

this known method has the disadvantage, that the lowering operation ofthe vibrator through these dense upper layers is highly time-consuming.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a method of compacting a loosely packed layer of earth, whereinthis drawback is effectively removed.

To this end, the method according to the invention is characterized inthat a tube is vibrated into the earth, said tube accommodating aclosing member at a distance from the underside of the tube whichsubstantially corresponds to the distance from the ground level to theupper side of the layer of earth to be compacted, earth being receivedin the tube while this tube is being vibrated into the earth, until thisearth within the tube strikes the closing member at the time that theunderside of the tube has reached approximately the upper side of thelayer of earth to be compacted, whereupon, in the further course of thetube being vibrated downwardly to the required depth, earth is displacedin the layer of earth to be compacted, whereafter the tube isvibratingly lifted and the earth which has been received in the tubeleaves the tube and is left in the ground.

According to the invention a hollow tube is applied, which producespractically no displacement of earth while being passed through thelayers situated above the layer of earth to be compacted, because theearth is received in the tube during this operation. This enables thetube to be lowered very rapidly through the upper layers. Only after thelower end of the tube has approximately reached the upper side of thelayer of earth which is to be compacted, the closing member prevents anyfurther penetration of earth into the tube, so that the tube from thenon functions as though it were closed at the underside.

Thus, while the lower end of the tube is being vibrated into the layerof earth which is to be compacted, the volume of earth displaced therebywill correspond to the volume of the earth-filled portion of the tubethat is received in the layer of earth to be compacted.

The tube, after having reached the required depth, is vibratingly liftedleaving the earth contained in the tube behind in the ground, so thatthe compaction resulting from the earth displacement is preserved.

By varying the lifting rate of the tube the supplementary compactionobtained by the vibration of the tube may be influenced.

The method according to the invention offers substantial advantages ascompared to the known method, if the density of the upper layers is ofsuch a nature that these upper layers need not be compacted themselvesand if the kinds of soil that occur in these upper layers are suitableindeed for use in compacting the underlying, loosely packed layer ofearth.

The invention further relates to an apparatus for carrying out themethod described hereinbefore. This apparatus comprises a tube withinwhich an intermediate closing member is accommodated, said closingmember being pervious to air.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will hereinafter beexplained with reference to the accompanying drawings.

FIG. 1 schematically represents the various phases of the methodaccording to the invention for compacting a loosely packed layer ofearth. 4

FIG. 2 is a partial vertical section of a first embodiment of the tubeshown in FIG. 1.

FIG. 3 is a partial vertical section of a second embodiment of the tubeshown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the invention, aloosely packed, noncohesive layer of earth, in particular a sand layer,superposed by dense layers of earth, is compacted. The location of thevarious layers is established beforehand 'by means of a probingoperation.

In the drawing the probing resistance in kg/cm is indicated on theabscissa, while the depth of the earth layers below the ground level inmeters is indicated on the ordinate. The result of the probing operationis indicated by the probing graph.

A tube 1, which is open at the underside and which has a diameter of,for example, 60 centimeters, is set up at ground level together with asuperposed vibrator 2 (Phase I), and is subsequently vibrated into theearth. A horizontal closing member 3, which is impermeable to earth, isfitted in the tube 1 at a distance a from the underside of this tube 1,which distance substantially corresponds to the distance from the groundlevel to the upper side of the layer of earth to be compacted.

This tube 1 receives earth 4 while being vibrated into the earth, untilthis earth 4 within the tube 1 strikes the closing member 3 at the timethat the lower end of the tube 1 has reached approximately the upperside of the layer of earth which is to be compacted (Phase II).

While the tube 1 is being vibrated further downwardly to the requireddepth, earth is displaced in the layer of earth to be compacted. Afterthe tube 1 has attained its final depth (Phase lll), the tube 1 isvibratingly lifted (Phase IV). The earth 4 which has been received inthe tube 1 remains behind in the ground, thus preserving the fullcompaction resulting from the earth displacement.

in order to allow the earth 4 contained in the tube 1 to be dischargedduring the lifting of the tube 1, the closing member 3 should bepervious to air, so as to prevent the appearance of a vacuum. Further,the closing member 3 should be permeable to water so that sub-soil watermay pass therethrough while the tube 1 is being vibrated into the earth.

The portion of the tube 1 situated above the closing member 3 may befilled with a liquid, in particular with water after the tube 1 has beenvibrated to the required depth but prior to the lifting of the tube 1.This liquid passes the closing member 3 while the tube 1 is beinglifted, which tends to improve the discharge of earth 4 from the tube 1.

In the embodiment shown in FIG. 2 the closing member is a perforatedtransverse partition plate 3', the size of the perforations beingselected in such manner, that no earth can pass.

FIG. 3 shows another embodiment of the tube 1, wherein the closingmember consists of a non-return valve 3", which is of particular valueif the distance from the ground level to the upper side of the layer ofearth to be compacted is smaller than the height of the layer of earthto be compacted. This non-return valve 3" comprises a valve plate 5,which is pivotally mounted on an eccentric transverse shaft 6 connectedto the tube 1. The valve plate is shown in the closed position whereinthis plate 5 contacts the stops 7. in its opened position the valveplate 5 abuts against a stop 8 and is downwardly inclined. When the tube1 is vibrated into the earth the valve plate 5 remains open until theearth received in the tube 1 comes into contact with the lower edge ofthe valve plate 5 and exerts a torque thereon. Due to this torque thevalve plate 5 is pivoted toward its closed position and prevents theearth received in the tube 1 to raise beyond this valve plate 5. Earth,in particular sand, is supplied into the tube 1 from the upper sideafter the tube 1 has been vibrated to the required depth but prior toits withdrawal, which earth passes the valve 3" while the tube 1 isbeing lifted and remains behind in the ground (Column 9).

The tube 1 is provided with a lower cutting edge 10. In order to preventclogging of the earth 4 in the tube 1 while the tube 1 is being vibratedinto the earth, supply means 11 may feed a lubricant, such as bentoniteor water, into the lower end portion of the tube 1, which lubricantreduces the friction between the earth 4 as it enters the tube 1 and theinner surface of the tube 1.

While the tube 1 is being introduced into the earth, a pressure mediummay be supplied through at least one supply pipe 12 which extends in thelongitudinal direction of the tube 1 and which ends near the undersideof the tube 1. This supply pipe is connected to the outer wall of thetube 1.

Although it is possible to use water under pressure as a pressure mediumduring the vibration of the tube 1 through the upper layers, it ispreferable in general not to use water, but a gas, in particularcompressed air, as a pressure medium as soon as the underside of thetube 1 has reached the layer of earth which is to be compacted.

The invention is not restricted to the embodiment described hereinabove,which may be varied in different manners within the scope of theappended claims. it is possible, for example, to vibrate an assembly ofseveral tubes into the earth at the same time instead of one single tube1.

1 claim:

1. A method for compacting a loosely packed layer of earth by a tubehaving a closing member therein at a distance from the lower end of thetube which distance substantially corresponds to the distance from theground level to the upper side of the layer of earth to be compacted,comprising the steps of: concurrently driving and vibrating the tubeinto the earth while permitting the tube to receive earth until thelevel of earth within the tube reaches the closing member and the lowerend of the tube concurrently has reached substantially the upper levelof the layer of earth to be compacted; then continuously downwardlydriving and vibrating the tube into the layer of the earth to becompacted to a predetermined depth for compacting the displacing theearth contained in the layer of earth to be compacted; and subsequentlyraising said tube while simultaneously vibrating the latter so as tocause the earth in the tube to be ejected therefrom to remain in theground upon withdrawal of said tube to replace the earth displacedduring said compacting step.

2. The method according to claim 1, comprising the steps of filling aportion of the tube located above the closing member with a liquid afterthe tube has been vibrated into the earth to the predetermined depth butprior to said raising of the tube, and passing said liquid through theclosing member while the tube is being raised.

3. The method according to claim 1, further comprising the steps ofsupplying earth into the upper end of the tube after the tube has beenvibrated into the layer of earth to be compacted, but prior to saidraising of the tube, and passing the supplied earth through a valveprovided in the closing member while raising the tube, so as to permitthe supplied earth to remain in the ground.

4. An apparatus for compacting a loosely packed layer of earthcomprising a tube; a cutting edge provided at the lower end of said tubefor facilitating the driving operation thereof into the layer of earthand a closing member located within said tube at a substantial distancefrom the lower end of said tube, said closing member being pervious toair.

5. The apparatus according to claim 4, wherein said closing member ispermeable to water.

6. The apparatus according to claim 4 wherein said closing member is aperforated transverse partition plate.

7. The apparatus according to claim 4 wherein said closing membercomprises a non-return valve.

8. The apparatus according to claim 4, comprising at least one supplypipe extending along the longitudinal direction of said tube and beingconnected to the outer wall thereof, said supply pipe having one endmounted adjacent the lower end of said tube and the other end adapted tobe connected to a pressure medium supply 10. The apparatus according toclaim 9, wherein said source. lubricant is bentonite.

9. The a aratus accordin t l i 8, comprising 11. The apparatus accordingto claim 9, wherein said supply means for feeding a lubricant into thelower end lubricant is waterportion of said tube. 5

1. A method for compacting a loosEly packed layer of earth by a tubehaving a closing member therein at a distance from the lower end of thetube which distance substantially corresponds to the distance from theground level to the upper side of the layer of earth to be compacted,comprising the steps of: concurrently driving and vibrating the tubeinto the earth while permitting the tube to receive earth until thelevel of earth within the tube reaches the closing member and the lowerend of the tube concurrently has reached substantially the upper levelof the layer of earth to be compacted; then continuously downwardlydriving and vibrating the tube into the layer of the earth to becompacted to a predetermined depth for compacting the displacing theearth contained in the layer of earth to be compacted; and subsequentlyraising said tube while simultaneously vibrating the latter so as tocause the earth in the tube to be ejected therefrom to remain in theground upon withdrawal of said tube to replace the earth displacedduring said compacting step.
 2. The method according to claim 1,comprising the steps of filling a portion of the tube located above theclosing member with a liquid after the tube has been vibrated into theearth to the predetermined depth but prior to said raising of the tube,and passing said liquid through the closing member while the tube isbeing raised.
 3. The method according to claim 1, further comprising thesteps of supplying earth into the upper end of the tube after the tubehas been vibrated into the layer of earth to be compacted, but prior tosaid raising of the tube, and passing the supplied earth through a valveprovided in the closing member while raising the tube, so as to permitthe supplied earth to remain in the ground.
 4. An apparatus forcompacting a loosely packed layer of earth comprising a tube; a cuttingedge provided at the lower end of said tube for facilitating the drivingoperation thereof into the layer of earth and a closing member locatedwithin said tube at a substantial distance from the lower end of saidtube, said closing member being pervious to air.
 5. The apparatusaccording to claim 4, wherein said closing member is permeable to water.6. The apparatus according to claim 4 wherein said closing member is aperforated transverse partition plate.
 7. The apparatus according toclaim 4 wherein said closing member comprises a non-return valve.
 8. Theapparatus according to claim 4, comprising at least one supply pipeextending along the longitudinal direction of said tube and beingconnected to the outer wall thereof, said supply pipe having one endmounted adjacent the lower end of said tube and the other end adapted tobe connected to a pressure medium supply source.
 9. The apparatusaccording to claim 8, comprising supply means for feeding a lubricantinto the lower end portion of said tube.
 10. The apparatus according toclaim 9, wherein said lubricant is bentonite.
 11. The apparatusaccording to claim 9, wherein said lubricant is water.